4.20-stable review patch. If anyone has any objections, please let me know. ------------------ From: J. Bruce Fields <bfields@xxxxxxxxxx> commit fdec6114ee1f0f43b1ad081ad8d46b23ba126d70 upstream. Zero-length writes are legal; from 5661 section 18.32.3: "If the count is zero, the WRITE will succeed and return a count of zero subject to permissions checking". This check is unnecessary and is causing zero-length reads to return EINVAL. Cc: stable@xxxxxxxxxxxxxxx Fixes: 3fd9557aec91 "NFSD: Refactor the generic write vector fill helper" Cc: Chuck Lever <chuck.lever@xxxxxxxxxx> Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/nfsd/nfs4proc.c | 2 -- 1 file changed, 2 deletions(-) --- a/fs/nfsd/nfs4proc.c +++ b/fs/nfsd/nfs4proc.c @@ -1016,8 +1016,6 @@ nfsd4_write(struct svc_rqst *rqstp, stru nvecs = svc_fill_write_vector(rqstp, write->wr_pagelist, &write->wr_head, write->wr_buflen); - if (!nvecs) - return nfserr_io; WARN_ON_ONCE(nvecs > ARRAY_SIZE(rqstp->rq_vec)); status = nfsd_vfs_write(rqstp, &cstate->current_fh, filp,
